U.S. patent number 4,173,372 [Application Number 05/840,716] was granted by the patent office on 1979-11-06 for dental chair.
This patent grant is currently assigned to Gary Reynolds, Harold Y. Tai. Invention is credited to Floyd E. Norris.
United States Patent |
4,173,372 |
Norris |
November 6, 1979 |
Dental chair
Abstract
A dental chair comprising a pedestal, a lifting assembly mounted
on the pedestal, a parallelogram assembly supported by the lifting
assembly, a seat assembly pivotally mounted on the parallelogram
assembly, and a backrest assembly pivotally mounted to the seat
assembly. The lifting assembly is capable of moving the
parallelogram assembly horizontally while simultaneously raising or
lowering it, thereby causing the seat and backrest assemblies to
move vertically without substantial horizontal motion. The seat
assembly is hingedly mounted to the parallelogram assembly and
includes a transverse shaft and drive means therefor. Means
separately link said shaft to the parallelogram and backrest
assemblies, such that rotation of said shaft by its drive means
causes simultaneous pivotal motion of the seat and backrest
assemblies, thereby permitting adjustment of the seat and backrest
of the chair to their most convenient inclinations for a given
dental treatment. The entire chair is rotatable on the pedestal,
and a locking means including an eccentric linking means is
provided for locking the chair in any rotational position.
Inventors: |
Norris; Floyd E. (Seattle,
WA) |
Assignee: |
Reynolds; Gary (Seattle,
WA)
Tai; Harold Y. (Everett, WA)
|
Family
ID: |
25283032 |
Appl.
No.: |
05/840,716 |
Filed: |
October 11, 1977 |
Current U.S.
Class: |
297/344.17;
248/421; 297/330 |
Current CPC
Class: |
A61G
15/02 (20130101) |
Current International
Class: |
A61G
15/02 (20060101); A61G 15/00 (20060101); A61G
015/00 () |
Field of
Search: |
;297/330,345,346,348,347
;248/421,419 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Zugel; Francis K.
Attorney, Agent or Firm: Dowrey & Cross
Claims
What is claimed is:
1. A dental chair, comprising:
a pedestal;
a lifting assembly mounted on the pedestal, said lifting assembly
comprising a base, substantially horizontal guide means mounted on
the base, elevation link means having first and second ends and
being pivotally mounted to the base at its first end, and elevation
drive means mounted on the base;
a parallelogram assembly including upper and lower members and a
plurality of parallel arms pivotally connected therebetween, the
length of said arms being longer than the distance between the
pivotal connections of said arms to said lower member, said lower
member being slidably mounted on the guide means and directly
connected to the elevation drive means such that said drive means
effects movement of said lower member along the guide means, and
said elevation link means being pivotally connected at its second
end to one of said arms between the midpoint of said arm and its
connection to said lower member in such a manner as to act in
reaction to the movement of said lower member along said guide
means for causing substantially vertical movement of the upper
member between raised and lowered positions when the lower member
is moved along the guide means;
a seat assembly mounted to the upper member;
a backrest assembly mounted to the seat assembly.
2. The dental chair of claim 1, wherein said elevation drive means
comprises an electric motor, a worm gear driven by said motor, and
a threaded collar mounted on said worm gear and linked to said
lower member.
3. The dental chair of claim 2, wherein the elevation drive means
further comprises elevation assisting means operatively associated
with the parallelogram assembly and with the lifting assembly such
that said elevation assisting means assists raising of the said
upper member and resists lowering of said upper member.
4. The dental chair of claim 3, wherein said elevation assisting
means comprises a spring mounted such that it surrounds the worm
gear.
5. A dental chair as in claim 1 wherein said guide means is an
elongated cylindrical member for insuring greater strength.
6. A dental chair as in claim 1 wherein said arms are displaced in
a vertical direction such that when the chair is in a lowered
position one arm is substantially above the other for creating a
low profile when lowered.
7. A dental chair, comprising:
a pedestal;
a lifting assembly mounted on the pedestal for rotation about a
vertical axis, said lifting assembly comprising a base,
substantially horizontal guide means mounted on the base, elevation
link means having first and second ends and being pivotally mounted
to the base at its first end, and elevation drive means mounted on
the base;
a parallelogram assembly including upper and lower members and a
plurality of arms extending therebetween, said lower member being
slidably mounted on the guide means and operatively connected to
the elevation drive means such that said drive means is capable of
causing said lower member to move along the guide means, and said
elevation link means being pivotally connected at its second end to
one of said arms for causing substantially vertical movement of the
upper member between raised and lowered positions when the lower
member is moved along the guide means;
a seat assembly mounted to the upper member;
a backrest assembly mounted to the seat assembly;
locking means mounted on the lifting assembly, said locking means
including a friction member, actuating means, and locking linkage
means connecting said actuating means to said friction member such
that the motion of the actuator causes said friction member to move
to and from a position in which it bears against the pedestal, said
locking linkage means being eccentrically connected to the actuator
for holding said friction member in a position in which it bears
against the pedestal.
Description
FIELD OF THE INVENTION
This invention relates to dental chairs.
BACKGROUND OF THE INVENTION
The great variety of treatments used in modern dentistry makes it
necessary for dental chairs to be adjustable so that the dentist
can position the patient in the most convenient and comfortable
position for each particular treatment. Particular adjustment
features should include provision for adjusting the elevation of
the chair above the floor, the orientation of the chair, and the
inclinations of the seat and backrest portions of the chair. The
elevation adjustment mechanism should be as compact as possible
without sacrificing strength and safety, so that the dentist's
knees can extend under the seat when he is working close to the
patient in a seated position. The adjustment mechanism for the seat
and backrest inclinations should be interrelated, so that the seat
and backrest are always automatically held in the best relative
orientation for patient comfort. All adjustment mechanisms should
be easy to use and should be as mechanically simple as possible so
as to reduce manufacturing and maintenance costs. Finally, the
dental chair should be comfortable and should be designed so that
it is as easy as possible for the patient to get on and off the
chair.
Although a considerable number of dental chairs have heretofore
been proposed, none of these prior chairs has been more than
partially successful in meeting these objectives. A number of prior
dental chairs have included a seat adjustably supported by means of
a paralleloram support structure. Although this structure is
comparatively simple, it suffers from the disadvantage that the
seat moves laterally as it is raised or lowered, a feature which is
not only inconvenient for the dentist but also requires a large
support structure so that the chair will be stable at all
elevations. Dental chair support structures have been devised which
reduce or eliminate the lateral movement during raising or lowering
of the chair, but at the expense of design simplicity and
reliability. A number of dental chairs have been proposed having
unitary mechanisms for controlling the inclination of the seat and
backrest of a dental chair. These chairs usually involve the chair
arms as part of the linkage mechanism. A disadvantage of this
approach is that the chair arms cannot be made so that they swing
out of the way to facilitate getting on and off the chair. Other
approaches to unitary seat and backrest inclination mechanisms have
involved almost prohibitive complexity. Finally, dental chairs have
been proposed which can be rotated about a vertical axis and locked
in any orientation, but none of such chairs have included locking
means which are convenient to use.
SUMMARY OF THE INVENTION
This invention provides a dental chair having simple, effective and
easily operated mechanisms for adjusting the elevation of the seat,
the orientation of the chair, and the inclinations of the seat and
backrest. The elevation adjustment comprises a simple parallelogram
design in conjunction with a novel lifting assembly which
essentially eliminates horizontal movement of the chair as it is
raised or lowered. The seat and backrest inclination adjustments
are interconnected via a simple and unique linkage so that a single
easy-to-use control automatically positions both seat and backrest
for maximum comfort and convenience. The dental chair is provided
with a novel and easy-to-use locking mechanism for selectively
holding the chair in any desired orientation.
The dental chair comprises a pedestal, a lifting assembly mounted
on the pedestal, a parallelogram assembly supported by the lifting
assembly, and seat and backrest assemblies mounted on the
parallelogram assembly. The parallelogram assembly includes upper
and lower members joined by arms such that the upper and lower
members remain parallel in all relative positions. The lower member
is slidably mounted on guide means supported in the lifting
assembly and may be caused to move along such guide means by an
elevation drive means also supported in the lifting assembly. The
lifting assembly further includes elevation link means pivotally
connected thereto and to one of the arms of the parallelogram
assembly. Such elevation link means translate movement of the lower
member along the guide means into vertical motion of the upper
member. The upper member carries the seat assembly, and thus
activation of the elevation drive means will raise and lower the
dental chair without any appreciable horizontal motion thereof.
The seat assembly comprises a seat frame hingedly mounted atop the
parellelogram assembly such that the seat can assume both elevated
and lowered positions. The backrest assembly comprises a backrest
frame hingedly mounted to the seat frame for motion between
reclined and upright positions. The seat frame carries a transverse
shaft, driving means therefor, and linkages connecting such shaft
to the parallelogram assembly and backrest assembly such that
rotation of the shaft causes the seat and backrest frames to move
in unison between their elevated and reclined positions and their
lowered and upright positions respectively. By such means, the seat
and backrest may assume a continuous but interrelated range of
positions for maximum versatility and patient comfort.
The lifting assembly is mounted on a pedestal such that the lifting
assembly can rotate about a vertical axis, so that the dental chair
can be easily rotated to any desired orientation. For locking the
chair in any given orientation, the lifting assembly includes
locking means including an actuator and a friction member connected
by locking linkage means. Operation of the actuator causes the
friction means to bear against the pedestal to prevent rotation of
the chair. The locking linkage means is eccentrically mounted to
the actuator such that the actuator will remain in the locking
position until removed.
These and other features, objects and advantages of the invention
will become apparent in the detailed description and claims to
follow taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the dental chair of the present
invention;
FIG. 2 is a perspective view of the dental chair of FIG. 1 with
coverings and parts cut away to reveal the adjustment
mechanisms;
FIG. 3 is a side elevational view of the pedestal and support
assembly of the dental chair of FIG. 2 with the chair in an
elevated position;
FIG. 4 is a top view of the pedestal and support assembly of the
dental chair of FIG. 2;
FIG. 5 is a side elevational view of the pedestal and support
assembly of the dental chair of FIG. 2 with the chair in a lowered
position;
FIG. 6 is a top view of the seat assembly of the dental chair of
FIG. 2;
FIG. 7 is a side elevational view of the seat and backrest
assemblies of the dental chair of FIG. 2 in their lowered and
upright positions respectively;
FIG. 8 is a side elevational view of the seat and backrest
assemblies of the dental chair of FIG. 2 in their elevated and
reclined positions respectively;
FIG. 9 is a perspective view of the locking assembly of the dental
chair of FIG. 2;
FIG. 10 is a partly broken away side elevational view of a portion
of the locking assembly of FIG. 9.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 presents an overall view of a dental chair according to the
present invention. The dental chair comprises a pedestal 10,
support assembly 12, seat 14, backrest 16, and armrests 20, 21. The
seat includes extended cushion member 15 to provide full length
support for the patient. The backrest includes headrest 17 and wing
supports 18, 19. The support assembly can be rotated on the
pedestal about a vertical axis, so that the dental chair can be
turned to any desired orientation. The support assembly itself
includes lifting means for varying the elevation of the seat. A
single adjustment means located in the seat allows the seat to move
between a lowered, substantially horizontal position and an
elevated position, while the backrest is simultaneously moved
between an upright and a reclined position. In FIG. 1, the seat and
backrest are shown in their lowered and upright positions
respectively.
FIG. 2 shows the dental chair stripped down to its support and
adjustment structures. The support assembly of FIG. 1 is seen to be
comprised of a parallelogram assembly 25 and a lifting assembly 35.
The lifting assembly is mounted on pedestal 10 by conventional
means (not shown) to permit rotation of the lifting assembly, and
therefore of the seat, about a vertical axis.
Referring now to FIGS. 2-5, the parallelogram assembly is comprised
of an upper member 26, a pair of lower members 28, 29, upper arm
pair 30a, 30b, and lower arm pair 31a, 31b. Connecting members 32a,
32b extend inwardly from lower arms 31a, 31b respectively for
connection to the lifting assembly as described below. Each arm is
pivotally connected at its upper end to upper member 26, the
connections for arms 30a and 31a being at points 34, 35
respectively (FIG. 3). The connections for arms 30b and 31b are
similar but not shown. Arms 30a, 31a are pivotally connected at 37,
39 respectively to lower member 28, and arms 30b, 31b are pivotally
connected at 38, 40 respectively to lower member 29. Members 26,
28, 29, and arm pairs 30a, 30b, 31a, 31b comprise a parallelogram
assembly. Such an assembly has the well known property that the
relative orientations of members 26, 28, and 29 will not change as
they are rotated about one another. Since, as described below, the
orientation of lower members 28, 29 does not change as the chair
elevation is adjusted, the orientation of the upper member, which
mounts the seat, will likewise not change. Thus the seat will not
tilt as the dental chair is raised or lowered.
Lifting assembly 35 comprises a base 52, guides 54, 55, elevation
link bar 60 (FIG. 3) and reversible electric motor 70. Guides 54,
55 comprise cylindrical tubes bolted to the base 52 such that the
guides are substantially horizontal. Lower members 28, 29 are
slidably mounted on guides 54, 55 respectively for substantially
horizontal movement thereon. Elevation link bar 60 is pivotally
connected to base 52 at pivot point 61 and to connecting members
32a, 32b at pivot point 62. Referring to FIGS. 2-4, it can be seen
that movement of the lower members 28, 29 along their respective
guides in the direction of pivot point 61 will cause elevation link
bar 60 to bear against and raise the arm pairs, so that upper
member 26 and the seat carried thereon will likewise be raised.
Similarly, movement of the lower members away from pivot point 61
will result in lowering of the upper member and the seat. FIGS. 3
and 5 illustrate such raised and lowered positions
respectively.
The configuration of the lifting assembly and parallelogram
assembly just described provides the mechanism for raising and
lowering the dental chair seat without substantial horizontal
movement thereof. Referring again to FIGS. 3 and 5, motion of the
entire parallelogram assembly towards pivot point 61 results in
horizontal motion of the upper member towards such pivot, while the
simultaneous upward swinging of the arm pairs tends to move the
upper member in the opposite horizontal direction. These two
motions cancel and yield a motion of the upper member which is
almost entirely vertical over the range of motion permitted by the
guides. To achieve such essentially vertical motion while at the
same time having lifting and parallelogram assemblies which are
compact in their lowered positions (FIG. 5), pivot point 62 between
connecting members 32a, 32b and elevation link bar 60 is preferably
closer to lower members 28, 29 than to upper member 26.
The means for moving lower members 28, 29 along guides 54, 55 is
illustrated in FIGS. 2-4. Such means comprises reversible electric
motor 70, gear reduction means 72, worm gear 80 and internally
threaded collar 85. Motor 70 is mounted to the gear reduction means
which in turn is mounted to base 52 by mounting means 73. The
output shaft 74 of the gear reduction means is journaled in plate
76 upstanding from the base. One end of worm gear 80 is also
journaled in plate 76, while the other end is threadably engaged by
collar 85. Pulleys mounted on output shaft 74 and worm gear 80 are
connected by flexible belt 78. Collar 85 is connected by yoke arms
88, 89 to lower members 28, 29 respectively. Thus rotation of motor
70 causes worm gear 80 to turn, which causes threaded collar 85 to
move horizontally thereon. Such horizontal motion is transmitted
via yoke arms 88, 89 to the lower members 28, 29, moving them along
the guides 54, 55.
Lifting assembly 35 further comprises spring 95 mounted therein to
assist motor 70 in raising the seat and to provide a backup safety
system should the motor or linkage thereto fail. The spring is
concentrically mounted about worm gear 80 and it extends between
threaded collar 85 and plate 76. Motion of the threaded collar
along the worm gear thereby causes compression or relaxation of the
spring so as to assist in raising the seat and to resist downward
motion thereof.
As previously stated, lifting assembly 35 is mounted on pedestal 10
for rotation about a vertical axis so that the dentist can turn the
dental chair to its most convenient orientation for a given task.
In order that the chair may be held fixed in position during such
task, locking means are provided for holding the lifting assembly
fixed in orientation with respect to the pedestal. Referring to
FIGS. 2-5, 9 and 10, such locking means comprises friction member
100, actuator pedal 102, and linkage therebetween. Friction member
100 is loosely mounted at points 101 to base 52 via shoulder bolts
103 and bushings 105 so that it can rock to and from a position in
which it bears against the pedestal. The pedestal has circular
symmetry so that friction member 100 will have a constant position
with respect to the pedestal during rotation of the lifting
assembly.
Actuator 102 is secured to shaft 104 which is journaled in block
106 upstanding from the base. Pin 108 is eccentrically mounted in
the end of shaft 104, such that rotation of the shaft via actuator
102 results in back and forth motion of pin 108. This back and
forth motion is transferred via link 110 into rotational motion of
lever 112 about pivot point 113 mounted in the base. Link arm 114
connects lever 112 to friction member 100, such that rotation of
the lever about its pivot point will move friction member 100 into
and out of contact with pedestal 10.
Referring now to FIGS. 1, 2 and 6, seat 14 comprises a seat
assembly 125 which provides the rigid support and adjustment
features of the seat. Seat assembly 125 comprises a seat frame 130
together with the structures, described below, mounted thereon.
Connecting plate 120 is mounted atop upper member 26 and secured
thereto by bolts or other suitable means. At its rearward corners,
plate 120 carries two internally threaded sleeves 123, 124. Seat
frame 130 is pivotally connected near its rearward end to plate 120
by pins 127, 128 passing through the seat frame into such sleeves.
Thus the rear of seat frame 130 is fixed to the support assembly
whereas the front of the seat frame may be pivoted upwards.
Reversible electric motor 150 and associated drive reduction means
152 is secured to seat frame 130 within the forward end thereof by
motor mounting bracket 153 and eyelet 154 extending from seat frame
130. Gear reduction means 152 supports one end of and drives worm
gear 155. The other end of worm gear 155 rides in internally
threaded collar 160 which is pivotally linked to transverse shaft
145 by means of yolk arms 162, 163 and pins 165, 166 (FIG. 6).
Transverse shaft 145 is journaled in shaft mounting bracket 140 at
points 172, 174. This bracket extends across the top of and is
secured to seat frame 130. Spring 176 and link 177 connect the
motor mounting bracket 153 and shaft mounting bracket 140 to reduce
motor vibration.
Lever arms 180, 181 extend from transverse shaft 145 and pivotally
connect with links 183, 184 respectively, such links being in turn
pivotally linked to connecting plate 120. Operation of motor 150
causes worm gear 155 to turn, which then rotates transverse shaft
145 by means of threaded collar 160 and yolk arms 162, 163
previously described. Rotation of transverse shaft 145 in a
counterclockwise direction (FIG. 7) causes lever arms 180, 181 to
push downward on links 183, 184, causing the entire seat assembly
125 to pivot upwards about pins 127 and 128 such that its front end
rises to the configuration shown in FIG. 8. Operation of reversible
electric motor 150 will therefore cause the seat assembly, as well
as cushion member 15 (FIG. 1) mounted thereon, to move between
lowered and elevated positions, as indicated by FIGS. 7 and 8
respectively.
Backrest 16 (FIG. 1) includes backrest assembly 210 which provides
the rigid support and adjustment features of the backrest. Backrest
assembly 210 comprises two members 212, 213 which extend therefrom
and pivotally connect to armrest supports 160, 161 which are part
of seat assembly 125. As is most clearly shown in FIGS. 2 and 6,
lever arms 190, 191 extend from transverse shaft 145 and pivotally
connect to links 194, 195 which links pivotally connect to links
198, 199 slidably contained in guides 163, 164. After passing
through such guides, links 198, 199 are pivotally connected via
links 202, 203 to members 212, 213. By such means, counterclockwise
rotation of transverse shaft 145 (FIG. 7) will cause lever arms
190, 191 to pull against linkages consisting of links 194, 198,
202, and 195, 199, 203 respectively to move the backrest assembly
from its upright position (FIG. 7) to its reclined position (FIG.
8). Clockwise rotation of transverse shaft 145 will push against
such linkages to cause the backrest assembly to move in an opposite
direction from its reclined to its upright position.
The combined motion of the seat and backrest assemblies may now be
described. Referring to FIGS. 7 and 8, counterclockwise rotation of
transverse shaft 145 in the position shown in FIG. 7 will cause the
seat assembly, comprising seat frame 130 and the structure carried
thereon, to rise with respect to upper member 26. At the same time
the backrest assembly 210 will rotate counterclockwise with respect
to the seat assembly. The result will be that the seat and backrest
assemblies will move in unison from their respective lowered and
upright positions (FIG. 7) to their respective elevated and
reclined positions. Thus by operation of reversible electric motor
150, by switch means not shown, the dentist can select from a
continuous range of interrelated seat and backrest positions to
place the patient in an optimum position for a given treatment.
The dental chair of the present invention includes armrests 220,
221 (FIGS. 2 and 7) rotatably mounted by depending cylindrical
members 224, 225 in tubular supports 227, 228. The tubular supports
are mounted on armrest supports 160, 161. Preferably, cylindrical
members 224, 225 contain slots (not shown) at their lower ends for
engaging stops (not shown) contained within the tubular supports,
such that the armrests are locked against rotating when in their
normal positions (FIGS. 2 and 7) but can be rotated by first
lifting them upwards such that the slots are moved clear of the
stops.
While the preferred embodiment of this invention has been
illustrated and described herein, it should be understood that
variations will become apparent to one skilled in the art.
Accordingly, the invention is not to be limited to the specific
embodiment illustrated and described herein and the true scope and
spirit of the invention are to be determined by reference to the
appended claims.
* * * * *